sunlight through the broken glass
by WhenLighteningStrikes
Summary: Heartbreak, fixations, pretences. They're a sort of cliché. Except not. Derek/Casey


_**a/n:** I was lying on the bed with a sore throat and fever and shtick and depressed because I just couldn't write anything. Worst writer's block ever. And then I wrote my longest one-shot yet...how's that for contrariness?  
__I hope you like the product of my fevered brow. :)_

**DISCLAIMER:** Disclaimed. Also, the 'seven smiles' thing is apparently in some movie, although I haven't seen it. So not only is the idea not original, as I'd thought, but it is also in the kind of movie that everyone has seen and no one remembers the name of. AND it's in a book too. Now let's go for gold...video game?

* * *

He rubs his eyes once again.

The image (nightmarish apparition) doesn't dissolve into nothingness as he'd hoped. If anything, it seems even more…_real_.

"I heard," she says, barging past him. Into _his _dorm. Sitting on _his _couch.

"Uhh…yeah," he says, "did you get lost by any chance? The way to the Klutzy Keener dorm is the other way."

She looks at him, dripping superciliousness from every pore, "I forgive you, Derek. I know you're not in the right frame of mind at the moment. Although 'mind' might be a bit of an overstatement considering your…"

"Yes," he interrupts hastily, before she can fully climb on to her favorite hobby horse, "Now go."

"I know that deep down inside you really want me to stay here and be there for you in your heartbreak, so I'm not going to go."

"No," he says (which dimension did he wake up in again?) "Deep down inside I really, _really _want you to go and _not _be there…" he stops, registering her words, "wait. What?"

She smiles triumphantly, "I heard about how Carla broke up with you. And I know that you're pretending to be okay, but really your fragile heart is six feet from the edge and thinking that maybe six feet isn't that far down."

He closes his eyes, "Please tell me you did _not _just quote Creed."

She looks put out, "I thought it was supposed to be…cool."

"By your standards," he says tightly, "Tinker was cool. So no comments. And for your information _I _broke up with Carla."

"Denial," she says, shaking her head sadly, "I knew you'd be shattered. So I brought you something."

She takes her other hand out from behind her back, smiling at him.

Chocolate Chip Ice-Cream.

"No, no, no, no, no," he moves back with both hands held out, "you don't. You _don't _get to…invalidate my man card."

"Derek," she moves closer, "I know you're hurting but…"

"Casey, just go _away_, okay."

She stops, and her hand is still held out comically.

(Except she's pouting and she's so _easy _to read and she's hurt and it's not comical at all).

"Fine," he says, "Stay. Whatever."

She claps her hands together and he tries to think of a situation where this would've ended differently. Where he'd have said something and they'd have fought and she'd have gone away. And he can't. Because it's him, and it's her and there isn't any way this night would've ended any other way.

(And they're a sort of cliché. Except not.)

* * *

See, here's what really happened:

Carla was blonde. And hot. And she was smart. And liked sex just as much as he did. And Marti liked her over the phone. And she wasn't related to Casey in any way. She didn't whine and over-analyze. And she didn't even _know _Casey. And it was…good, you know.

(And she broke up with him. And that's okay. He isn't heartbroken or anything. He's Derek).

And so what if she broke up with him over a fancy dinner where he used the word _exclusive _for the second time since he can remember_. _

It's okay.

Really.

* * *

"It's not okay, Derek."

He's trying to tune her out. (He never tuned Carla out. And she left him. Which is fine).

She gets up and switches off the television. "Are you listening to me?"

"How do you know anyway?"

"What?" She scrunches up her face and the familiar gesture makes his insides clench painfully.

"Me and Carla."

"Oh…I heard from…someone," she says vaguely.

He stands in from of her, arms crossed, "Mind telling me what this is _really _about?"

"My roommate has someone over," she says in a rushed voice.

"So?" he says blankly, "You could have joined them for a stupid girl-talk session or whatever."

She blushes and it's not insanely endearing or anything, "It wasn't a girl."

"Oh," he says, comprehension dawning in his eyes with all the subtlety of Ralph at an Irish Dancing competition, "Oh." And then suspiciously, "So where are you staying for the night?"

She opens her (stupidly blue) eyes wide, "I was just thinking…we don't spend enough time together...

(_What?_)

"…and since we've come to a general consensus on our being siblings, I think we should start _behaving _more like siblings and helping each other out. And I think I can help you here."

He stops for a moment and looks at her not looking at him. And for that split second he's back in their suffocating kitchen. And he doesn't take the bait.

"You're going to give me _girl _advice?"

"Yes. Since I'm a girl and I obviously know better."

Sometimes she really just _asks _for it. "That's arguable."

She looks offended, "_Of course _I know better."

"Not that," he says, "that you're a girl. I didn't know they had genders on your planet."

She sits (too) close beside him on _his _couch, and there's really not enough space for her and him and her (too long) legs, "Is that the best you can come up with?" she asks, sympathetically, "You must really be heartbroken."

"You're admitting I have a heart?" So what if he's not at the top of his game. It happens to the best of them occasionally.

And suddenly, without as much as a preliminary warning, her head is on his chest and that debatable organ threatens to take a flying leap out of his body.

She raises her head again (and doesn't look at him and maybe he should tell her that he doesn't need to look into her eyes to know what she's feeling. He knows her better than anyone ever will) and says quietly, "sounds to me like you do have a heart. Is that in contradiction to your lifelong beliefs?"

He doesn't have to answer (he couldn't have, anyway) because:

"Am I interrupting something?"

He looks up, and for a strange, crazy moment he wants to tell Jake that he _is _interrupting.

"Oh, nothing at all," says Casey McPerky, "Hi! I'm Casey McDonald. Derek's stepsister."

Jake looks at her for a moment and Derek can almost feel his eyes taking her in (blue eyes and long legs and all) and he never quite realized with such alacrity how perfect Jake's face would look with a black eye.

"Dude," Jake turns to him, suspiciously, "She isn't cross-eyed."

"Cross-eyed?" He speaks over her exclamation of indignation, "I must've confused that with ugly."

"But," says Jake looking confused (it's a worn-out expression), "She's not ugly. You're not ugly;" he informs her, "don't listen to Derek."

"Oh, I _never _listen to Derek," she says, and he's never quite realized how annoying that gratified look of hers is. And about _this_, what any brain-dead moron (the resemblances with Jake are astounding) with a half-way functional eye-sight could have told her.

He wonders sometimes what she sees when she looks in the mirror.

Jake, obviously unable to comprehend the simple concept of 'not interested' (so what if she's twirling a strand of her hair and smiling in that inane way, it doesn't have to always mean anything) goes on, "So…I was thinking of going out for Chinese…maybe you could join me?" (Fast worker is obviously an understatement).

And he realizes with a sickening lurch that she's going to accept. Not that he _wants _her here. He'd rather be alone with the remote, his couch (and Carla might call, not that he's waiting, because that'd be lamer than Casey's current smile), but she's never yet left him for anyone else and he's not about to change an order that works.

He takes a long deep sigh, and turns to Jake, "Get me a can of beer before you go."

Casey turns towards him uncertainly, "Beer? But when you're heartbroken you always have milk and cookies."

"I don't feel like it," he maybe should care a little more that Jake's laughter probably means he's lost his college rep.

"Derek, what's the matter?" She's standing directly in his line of vision and he's too tired to turn his head away.

"No," he says, "Go, okay. Whatever, you should go." And means it. He doesn't always want (need) Casey around to deal with everything in his entire damn life. He had a life before he met her, didn't he?

Jake holds the door open for her, "After you."

She glances a moment at the open door and he can almost see her trying to remember how many other guys have held doors for her. Then, she resolutely turns away from temptation and looks at him. "No, I think I'll stay in tonight, I'm a little tired. Thank you, though."

And he shouldn't. (But he does). Feel an absolute, overpowering sense of victory.

Jake's face is a study in disappointment, "So, maybe the…poetry club gathering tomorrow?"

What. The. Fuck.

Her face lights up, and he can see her internal struggle to not show her appreciation, (Faking Casual is one of the subjects in Casey 101, which he aced), "Yeah…maybe."

He leaves (finally) but he's still here in Casey's soft irritating smile.

**ooooo**

"You should have gone," he tells the TV screen.

"Like that wasn't a maneuver to get me out of your dorm," she rolls her eyes, "not like you're too obvious or anything Derek."

"Yeah, whatever."

"I hate that word," she flounces a bit before settling down, "and there's that whole blood thicker than water thing so I couldn't have gone."

"Casey," he turns to her "we don't share _blood_. Your sick family fantasy is out of control."

"And anyway," she ploughs on with a determination worthy of an actual cause, "We've got to stop your vicious cycle. You know, all the girls you like leaving you- Sandra and Amy and Sally and Celeste and Kylie and Carla and…"

"You're _really_ making me feel better here," he retorts sarcastically, "thanks Case."

"You liked Carla a lot, didn't you?" And maybe if she didn't say it in _that _tone- soft and gentle, like she cares or something. Not Derek Venturi forced (step) brother but...Derek...maybe he'd have more resistance.

He shrugs, expression blank, "Girls, they come and go. I don't really care. _You_ should know that."

And they came and went. It wasn't a big deal or anything. He always got what he wanted, didn't he. So what if he couldn't keep it.

She sighs, like she…knows him or something. It's irritating. He doesn't like being read and slogged over like one of her freaking assignments.

She hugs him (tries to), he pushes her away. It's so scripted he doesn't even need to look any longer. Except she falls on top of him. "Face it, D. Your aim and all those hockey skills are so shot." She strings her fingers through his hair and pulls affectionately, and sighs in exaggerated longing "If only the high school crowd could see you like this."

He moves away a little, uncomfortable. Earlier, he used to think her little gestures and excessive need to hug were in direct defiance to his 'no PDA' rule. It was only after having lived with her for a while that he realized; she just…_liked _to touch, being touched. She liked being held, kissed on her cheek or simply entwining hands with anyone. It was a Casey-thing, like neurotically submitting assignments before time and wearing blue eye-shadow to impress.

And sometimes, when he thinks about it, which he doesn't really, he thinks she'd really like sex. She'd like all the slow touching and building and just the feel of tangled bare skin. She'd like exploration and the discoveries. She'd like the intimate feeling of belonging and being wanted.

She never shouts when she's furious with him. She doesn't call him De-_rek _or refuse to talk to him. In her moments of absolute hurt and anger, she just refuses to let him touch her. She flinches from his hand at her shoulder and subconsciously moves away when he moves a little close. He's not sure she knows this herself; touching to Casey is different kinds of love.

He pushes her again, and succeeds this time.

"Maybe you should stop trying to…I dunno…_fix_ me or something, and go out with someone yourself."

"Like the poetry club with Jake?" She bites her lip in thought (she does it a lot. It's annoying).

"Yeah," he says seriously, "you should go out with him. He's perfect for you."

She glances at him guardedly, "Really?"

"Yeah," (sometimes he wishes he _didn't _know her like he does), "It's like that made for each other shtick. He likes everything you like. He's a nice guy. Decent. Polite. You should really get to know each other."

Her glance turns to a full-blow glare of suspicion, "You think so?"

"I know so," he says sagely.

(She won't be listening to any poetry tomorrow. He's not exactly sure what he got out of it.)

**ooooo**

She stays over and talks about Carla and feelings (and love, like she knows what it is) and he laughs. She talks about same differences and shared siblings and duties and responsibilities and he laughs harder. She gets mad, and he does everything he can to make her keep the look (it's entertaining). She threatens to leave (he opens the door).

(She still sleeps on the couch and he doesn't offer her the bed and he doesn't get up thrice in the night to get drinks of water that he doesn't need).

* * *

Here's what you should really know about his crazy (step) sister:

She hasn't ever known when to leave well enough alone.

(Here's another thing which you don't absolutely _have _to know; she has seven kinds of smiles).

* * *

Their table is secluded and she's exactly his type. (She's redheaded and hot, right?) And he has expectations from the evening. He's not going to spend his entire life in his dorm waiting for Carla to visit.

He's leaning in…and his mobile beeps.

"Excuse me," hey, he can do polite (it's not like it'll be Carla or anything, it might be an…emergency).

_Message received at 10:25 pm  
__Go for it, D!  
__-Casey_

And maybe he should be appalled he can recognize her in a blonde wig, with her back towards him, but he's Derek and he doesn't overanalyze (that's her job).

He pays the bill and seats the redhead (she has a name, which he knows, he's just…tired) in a cab. (Maybe she'll think he's a gentleman and doesn't kiss on the first date. It's all good).

He goes back. "You're unbelievable. What the _fuck_ do you think you're doing?"

"You didn't kiss her," she says, sounding strangely…dissatisfied.

"Yeah, I _would _have and maybe have gone further if my stepsister hadn't taken it in her insane head to stalk me. You can't find a guy so you're going to live through me vicariously?"

She blinks at his use of the word and he can almost _feel _her biting back retorts on his general IQ, "You should have kissed her. It would've shown Carla you're over her."

"Yeah," he looks at her in disbelief, "except she isn't here."

"Derek, she's just a _girl_," she's frustrated, "You don't have to be faithful to her memory."

"Are you _serious_?"

"Do you generally pick up your mobile in the middle of an anticipated make-out scene?"

He suddenly has trouble looking at her, he wasn't being _faithful _or anything, he _would _have kissed his date. He really would have. If she hadn't been here and watching him. After all he…hates PDA, right?

"And I missed out on research," she says, "I thought maybe there was something wrong with your kissing style and that's why they all keep leaving you."

She's taken off her wig and taken out a notepad instead and three different colored pens and she's wearing her reading glasses and it's all so (achingly) Casey.

"There's nothing wrong with my kissing style, thank you very much," he informs her, and to be honest, he's a little amused.

"They all think that," she mutters and she's holding the pen in her hand at an odd angle.

He pulls her hand closer and observes a jagged cut till her wrist, "What the hell happened?"

She flushes, "I accidentally…the knife was a little sharp."

"Klutzilla," he looks at her hand again, "and why haven't you bandaged it?"

She flushes even more (he'd have thought it was an academic impossibility), "Because it just happened and you were _going _to kiss her and I didn't want to go away during that." And she glares at him, "and then you _didn't _kiss her, so it's all your fault that I have a cut hand and no research material."

"Want me to kiss it and make it better?" Hey, he does it for Marti, right? It's all the same difference.

And it's sarcastic but he knows it's a challenge. And she knows it too. (Challenge is practically the defining word for their…whatever it is).

She raises her head a little higher, "Yes please, o' brother of mine" she says in quiet defiance.

He looks at her all the while and trails close-mouthed kisses along the cut. It's soft and something else and a punch to the gut and she snatches her hand back almost immediately, holding it against her body. And he feels an odd discontentment of having missed out on something in the moment. Like an irritating tune at the back of his mind that he just can't place.

"It's all better now," she says breathlessly, childishly.

"Yeah, well, my kisses are mind-blowingly numbing." It doesn't really have the same kick to it.

She rolls her eyes, exaggeratedly, "Yeah, whatever."

"I thought you hated that word."

"It's the only one I can think of when I think of you."

They say a lot and they don't say a lot and they still know it. And when he thinks about it (which he doesn't) it's a little sad.

* * *

Here's something that everybody almost always gets wrong:

He knows he doesn't think of her as his sister and 'same difference' is laughable. But that's okay, it doesn't mean anything. There are a lot of people whom he knows and they're not friends or enemies (or siblings), they just _are_. They exist and he exists and the world still turns. Not every relationship has a title. She might not be his sister, but that isn't to say she's anything else.

He almost believes it himself sometimes.

* * *

"You _do _realize you spend more time in my dorm than you do in yours," he informs her, just in case she's missed out on it.

"It's all your fault."

"Because I stand here breaking out the red carpet for you, princess," hadn't the whole point of the college thing been to get _away _from each other?

"No," she glances briefly from the book she's reading on the other side of _his _bed, "it's just that I wouldn't put it past you to slash your wrists or something. You're melodramatic enough for it. And originality is definitely not one of your strong points."

"You're saving me from myself," he mutters mockingly, "very original."

"And now that you've reminded me, I _do _have somewhere to be tonight. So if you'll excuse me," she gets up from his bed, her body imprinted in the dent.

"Where," he asks unconcerned.

"Somewhere dressy. So if you could go out, I can change." She makes a shooing motion with her hands. (And maybe he should be worried her 'dressy' clothes are hanging in _his _closet).

"No." Simply.

She sighs, and he knows she hadn't expected him to listen, "Fine, whatever. Where's the common bathroom?"

He doesn't think about it, "You can change here."

Her face scrunches up in confusion for a second and then her eyes widen with implications (it's all semantics), "What the hell Derek."

"No, really" his hands are cushioning his head, watching, waiting, whatever, "I don't mind."

"I'm not going to change in front of you," she doesn't raise her voice.

"Why, Casey," mocking tenderness, it cuts, "Same difference, right? What kind of siblings would we be if we don't even see each other _change_? That's practically the foundation of siblinghood."

He keeps his mind carefully blank and he's not going to think it out or acknowledge crossed lines and betraying words.

"Derek…" her voice shakes a little.

"What's the matter Case?" It's point blank, no evidence of mockery, "You've established it. Now prove it. Or is it easier to use words than mean them?"

She stares directly at him (clash of blue), "I dislike you intensely."

He shouldn't notice she doesn't use the word 'hate', but he does.

Her hand is at the top button of her shirt and he'd been absolutely sure she wouldn't do it. And quite suddenly it's hard to swallow. He can't tear his eyes from her hand moving down her shirt, exposing, the only outward indication that she's affected in any way is the slight trembling of her hand. And till that very moment he'd been sure he wouldn't be involved in it. It had just been a culmination of the straight month in which Carla hadn't called and her constant presence which meant he couldn't even pretend to himself because of her uncomfortable habit of calling him out.

He hadn't ever really thought of her as anything. He didn't classify her as female at all and all maybe ifs would have just been lame excuses. To him, she'd been an (almost) asexual being and he had found it inexplicable that sane guys whom he knew and liked could be interested in her. She was related to him by paper and lived in his house and he sort of, grudgingly, cared for her, and couldn't bear to see her cry. But that had been it.

But seeing her vulnerable (and soft and warm and _female_) he can't stand it. Four years of blue and pink lines and high walls dissolving. Before she reaches the last button, he rushes out of the room and sinks against the door, sweating, his heartbeat alarmingly erratic.

It could've been minutes, hours, (years) before she comes out again. She's still wearing the same shirt, buttoned again, steadily avoiding touching him, and there's this moment where he thinks she's going to walk out without looking back at him.

She holds the door knob in her hand and looks at him tiredly, "You know what, Derek. Out of all of them, I've never left…"

Fuck.

"…but maybe I should have too."

And leaves.

**ooooo**

Carla calls three nights later (remind him to laugh at the irony sometime).

He listens to her apologies, because this is what he wanted and he's (once again) going to get it.

"…so sorry, I don't know what came over me. I just…got scared and…"

He can't hear her for the most part over the sound of his own pounding heartbeat, and in between all the not remembering.

"De-_rek_, are you even listening to me?"

And for a moment it's all white noise rushing past and, "Say…say that again."

"_What_," she snaps, exasperated, "I'm sorry okay, baby, I…"

"Not that," he cuts her, "Say my name."

Her voice softens noticeably, "Derek."

"No," he says in frustration, "not like that. Break it."

"De-rek?" she offers, confused, "It's what I always call you when I'm mad, you know that."

(Carla is blonde. And hot. And smart and intelligent. And likes sex just as much as he does. And Marti liked her over the phone. And she isn't related to Casey in any way. She doesn't whine and over-analyze. And she doesn't even _know _Casey. And it is…good, you know.

She's nothing like Casey but she breaks his name and he knows now).

* * *

He's smashing stereotypes here, but you should really know this:

So he lies a lot and he doesn't realize things half the time, but he's not stupid.

* * *

If he'd been the director, he'd have kept the library out of the entire equation. But she isn't given to following his stage directions anyway.

And maybe the costumes would've been different. She's wearing her stupid glasses and those bunny slippers which should be made illegal for their crimes against human vision. But it's all...her. And he can't think of anything different.

He shoves his hands in the pocket of his leather jacket, "I'm not going to write you any love songs."

She snorts and doesn't look up from How To Be Lame(er) or whatever the hell she's reading, "I can do without odes to my knees and sneezing habits. I've seen your efforts; they're not pretty. In fact it should be made criminal for you to write romantic songs. I don't want them."

(She doesn't need them).

"Just so we're…clear on that."

"And I would rather tap-dance naked in front of Truman than wear that hygiene disaster you call a jacket."

"Whatever. And you're out of your mind if you think I'm going to eat rabbit food for you."

She snorts again, "Believe me, Derek; I stopped believing in miracles the day I met you."

* * *

So anyway, if you can keep secrets; he might let you in on one:

She has seven kinds of (lame) smiles.

(And four of them are only for him).

* * *

_Fin._

* * *


End file.
